1. Field of Invention
This invention relates generally to the reclamation of used fossil fuels and more specifically to an improved process and related apparatus for ridding contaminated motor oil of common pollutants.
2. Prior Art
A number of methods and processes for removing dirt and other performance inhibiting contaminants from motor oils are known in the art. One of the first of these processes is described in U.S. Pat. No. 2,196,989 awarded to Henry and Montgomery. The '989 patent discloses combining the oil to be treated with a light hydrocarbon solvent, such as propane, to form a two phase solution.
The first phase, a substantially oil/solvent solution phase, rises above the second phase, a substantially asphalt phase, because of the difference in specific gravities. One or more of a group of gases such as methane, ethane, hydrogen, carbon dioxide and nitrogen is then added to the first phase to act as a precipitant for the oil and further remove undesired components. The '989 patent shows a closed system, thus allowing for reuse of the solvent and gas.
However, while the process of the '989 patent appears somewhat effective in removing asphaltic materials from used oils, it disclosed no method for removing other environmentally dangerous contaminants therefrom, such as lead. Additionally, the '989 process appears to be effective only if used on a large scale.
A second relevant patent indicative of more modern developments in the prior art is U.S. Pat. No. 3,870,625 issued to Wielezynski. Therein is disclosed a method for cleaning lubricant oils comprising spraying the used oil in pulses into a column where propane is simultaneously introduced. After settling of unwanted material by gravity to the bottom of the column, the propane/oil solution is transferred to another column in which the process is repeated. A series of columns allows for multiple repetitions. Finally, the propane is separated from the oil for future use by vaporization of the former.
The '625 patent, similar to the '989 patent, discloses no method of removing lead and other metallic substances from the contaminated oil, thus severely limiting the scope of use of the regenerated oil. Also, the fact that several columns are utilized hinders the economic and efficient use of space.